Internet is the global network of computers connected by network cables or satellite signals.
  • It is a network of networks so called super network.
  • ARPANET (Advanced Research Projects Agency Network) is the world's first operational packet switching network which is predecessor of Internet.
  • WWW (World Wide Web) is developed by Tim Berners Lee in 1989 while working at CERN.
  • WWW is a communication model used to exchange information over Internet.
  • URL (Uniform Resource Locator) specifies the unique address of resources over Internet.
  • Search engine is a website that helps users to locate their searched information over world wide web.
    E.g. Google, yahoo, bing, baidu,, AOL, excite, DuckDuckGo, Wolfram Alpha, Yandex, Lycos and Chacha
  • A web browser is a software application to access the information on WWW.
    E.g. Google Chrome, Firefox, Safari, Internet Explorer and Opera.


Protocol is a standardized set of rules used for network communication. Below are few major protocols.
  1. TCP - Transfer Control Protocol
  2. IP - Internet Protocol
  3. POP - Post Office Protocol
  4. SMTP - Simple Mail Transfer Protocol
  5. HTTP - Hypertext Transfer Protocol
  6. FTP - File Transfer Protocol
  • TCP/IP allows to transfer information over Internet, by breaking data into smaller pieces called packets.
  • IP address is unique code assigned to each computer. It is of 4 numbers separated by a dot and each number is in the range between 0 to 255. E.g.
  • POP allows to receive mails.
  • SMTP allows to send mails.
  • HTTP protocol allows to access web pages as a connection between web client and web server.
  • FTP allows to transfer files from one computer to other.


Email is a service to exchange the messages/information among people over Internet. It is invented by Ray Tomlinson.
  • It has limited usage in 1960s and full usage in 1970s.
  • Email address is in the form of username@domainname. E.g.
  • Email addresses are not case sensitive.
  • From - indicates sender's email address.
  • To - indicates recipient's email address.
  • CC (Carbon Copy) - indicates the recipient's email addresses who are to be informed but not a direct recipient.
  • BCC (Blind Carbon Copy) - indicates recipent's email addresses but hides recipient email addresses from each other.